Buried vertical threaded exchanger for heating or cooling apparatus

ABSTRACT

A hollow pile suitable for being sunk substantially vertically into the soil by screw-sinking, said hollow pile being characterized in that it has: at least one helical fin ( 2 ) having a flattened shape and a small pitch suitable for causing the pile to be sunk by a few centimeters per turn, when said pile is caused to move in rotation, the helical fin ( 2 ) finding itself united mechanically with and in thermal contact with the outside wall of the pile ( 1 ); and internal partitioning ( 3 ) defining an axial compartment ( 11 ) and an outer compartment ( 12 ) that communicate with each other at the bottom ( 13 ) of the pile; said hollow pile being characterized in that: the helical fin ( 2 ) is in direct thermal contact with the outer compartment ( 12 ) through the thickness of wall of the pile ( 1 ); and the outer compartment ( 12 ) has a flow section (S 2 ) that is significantly smaller than the flow section (S 1 ) of the axial compartment ( 11 ).

The field of the invention is shallow and medium-depth geothermalengineering. Consequently, the invention may also apply to layingfoundations for buildings.

In the field of shallow and medium-depth geothermal engineering,air/soil or liquid/soil heat exchangers are known that are used inheating or air-conditioning installations and that are currentlyconstituted either by sheets of tubes made of plastics materials or ofmetal and that are buried to depths of a few tens of centimeters, orelse by vertical tubes, or indeed, in certain situations, by verticalpins.

Such heat exchangers pass a heat-transfer fluid. The heat-transfer fluidcan be water, or water to which antifreeze and/or corrosion inhibitorshas/have been added, or indeed a refrigerant of the category constitutedby ammonia, by carbon dioxide, and by fluorine-containing compounds.

Devices known as “Canadian wells” or “Provencal wells” are also known,in which air is caused to pass through underground pipes placed atdepths generally lying in the range 1 meter to 3 meters before the air,as moderated in temperature by passing through the soil, is fed into abuilding.

Implementing such prior art heat exchangers requires considerableearthworking means and is thus particularly costly. In addition, theperformance of the heat exchangers depends directly on the surface areasof tubes in contact with the ground, that surface area being limited, byconstruction, to the surface area of the outside walls of the tubes,which walls are strictly cylindrical. Under all circumstances, such heatexchangers represent a pure extra cost, insofar as their sole functionis to contribute to operation of the heating and/or air-treatmentsystems equipping any given building.

A main object of the invention is to improve the performance offluid/soil heat-exchangers used in making heating or air-conditioninginstallations for buildings, regardless of whether said buildings areindividual or collective residential buildings, service sectorbuildings, or industrial or agricultural buildings, or indeedlightweight buildings for residential leisure use.

A further object of the invention is to reduce the prices of fluid/soilheat exchangers while also increasing the life spans of such heatexchangers.

An additional object is to enable fluid/soil heat exchangers to beimplemented rapidly without requiring the use of excessive earthworkingmeans, and in particular to enable such heat exchangers to be installedin small plots of land or even directly under buildings that are alreadybuilt, or indeed, in plots of ground areas that are fully occupied bybuildings.

An additional object consists in facilitating building of lightweightconstructions while also improving the thermal performance of suchconstructions.

In order to achieve these objects and others that appear on reading thedescription of embodiments and uses of the invention, the inventionproposes to implement heat exchangers by means of screw-sunk metalpiles, similar to those used for laying foundations for lightweightconstructions. Such an embodiment, which is particularly inexpensive,makes it possible to increase the working heat-exchange area and thusthe effectiveness of the heat exchangers. In a preferred embodiment, thescrew-sunk metal piles have two functions in that they act both asbuilding supports and also as heat exchangers for feeding theheating/air-conditioning systems of the buildings in question.

The invention is based on using hollow metal piles that have bottom endsof conical shape, and that are provided with mainly horizontal fins ofhelical shape, said fins having large surface areas and relatively smallpitch (typically and in a manner lying within the prior art for layingfoundations for lightweight constructions, pitch of a few centimetersper turn, so as to make it possible to put the piles into place byscrew-sinking).

In the following description, it can be seen that the objects ofreducing cost are achieved by using tried and tested installation andimplementation methods that are designed for laying foundations and/orwhile combining the foundation function with the heat-exchangerfunction. It can be observed that the objects of improving efficiencyare obtained by means of the action of helical fins that contribute toincreasing the area of contact between each of the tubes and the soil,and therefore to increasing the quality and effectiveness of heatexchange, while also, when using the piles of the invention both as heatexchangers and as foundation elements, procuring a bed that isparticularly resistant both to pushing-in forces and to pulling-outforces. It can also be observed that said helical fins offer not onlythe advantage of enabling the piles of the invention to be put intoplace rapidly and inexpensively since they can be put into place bymeans of a simple screw-sinking machine, but also the advantage ofsignificantly increasing the area of contact between each of the tubesand the soil. In addition, it can be seen that the specific featuresrecommended by the invention make it possible to increase the mass ofmaterials involved in the heat exchange between the fluid and the soil,by putting materials into place, around the peripheries of the piles,which materials are adapted to facilitate such heat exchange, while alsomaking it possible to strengthen the anchoring of the vertical piles inthe soil.

In the invention, the mainly horizontal helical fins have threefunctions:

1) they enable the piles to be sunk by screw-sinking whenever said pilesare subjected to high rotary torque by means suitable machines ortooling;

2) they constitute bearing surfaces suitable for improving theresistance of the piles to being pushed deeper and/or pulled out oncesaid piles have been sunk into the soil; and

3) they improve the area of heat exchange between the outside wall ofthe pile, with which wall they are in thermal contact, and the soil intowhich said pile has been sunk by means of the screw-sinking operationsmade possible by the presence of said fins.

Additionally, the piles of the invention are provided with mainlyvertical fins that serve to push away the earth or the mineral mattermaking up the soil to a distance corresponding to the width of saidmainly vertical fins relative to the outside walls of the piles. Once apile has been put into place by screw-sinking, the resulting spacegenerated as the piles are being sunk into the soil may be filled with asuitable material, e.g. lean cement, bentonite, or a substance thatchanges state. This suitable material offers the advantage of presentingconductivity that is greater than the conductivity of earth.Advantageously, it may also present high specific heat. In a variantoffering particularly good performance, this material is constituted bya material chosen from paraffins, or from substances having the propertyof storing and of delivering large quantities of heat on going fromtheir solid states to their liquid states, or from their liquid statesto their solid states.

Putting the piles into place by using a suitable machine that enables afirst segment of tube provided with a tapering and pointed or conicalbottom end to be subjected to thrust and rotation forces has the effectfirstly of causing said segment to penetrate into the soil, under theeffect of the mainly horizontal fin with which said segment is provided,and secondly of pushing away the earth at the periphery of said tubeunder the effect of the mainly vertical fins that compact the earth thathas been broken up by the mainly horizontal fin and that form an emptycylindrical sheath between the outside wall of the pile and the cylinderof compacted earth. Once this first segment, which preferably has alength of about 3 meters, has been sunk into the ground, it is possibleeither to use it as it is by equipping it with internal partitioning andwith a flange plate at its top, or to extend it with one or moreadditional segments, each of which may also have one or more mainlyhorizontal fins making it easier for them to penetrate into the soil andone or more mainly vertical fins pushing away and compacting the earthat the periphery of the tube. The additional segments are assembled tothe bottom segment by crimping, by inter-fitting, by welding, or byscrew-fastening. In any event, said segments are assembled together suchthat the resulting pile has the same shape as a single tube providedwith a pointed end and with a plurality of mainly horizontal fins and,optionally, but particularly advantageously for the performance of theinstallation, with one or more mainly vertical fins. The resulting pileis sunk until its top end comes flush with the ground level, or indeed alittle more deeply, in which case the soil is dug out down to a depth ofabout 50 cm. The pile is then equipped with internal partitioning,defining an axial compartment and an outer compartment, and with aflange plate at its top, through which flange plate the pipes pass thatmake it possible to feed fluid to the inner and outer compartments. Inthe particularly advantageous situation when the tubes forming the pilesare equipped with mainly vertical fins, there exists a space having theshape of a hollow cylinder between the outside wall of the tube and thecompacted earth that has been pushed away at the periphery of the tubeby the action of said mainly vertical fins. The space is mainly occupiedby the mainly vertical fin(s) and it can be understood that, in thiscondition said mainly vertical fins cannot effectively enable heat to betransmitted between the soil and the fluid flowing through the internalcompartments of the piles. That is why the invention recommendscompletely filling the empty space generated by the mainly vertical finsmoving in rotation. This filling is performed with a material that, atthe time it is put in place by being cast, has viscosity sufficient tofill the entire void lying between the outside wall of the tube and thesurface of the compacted earth. For example, the filling may beperformed with:

-   -   a lean mortar or cement;    -   a resin preferably filled with conductive particles (e.g. with        iron filings or carbon fibers);    -   a material of the bentonite type or of some equivalent type; or    -   a material having the property of changing state at positive        temperatures, preferably close to 20° C., so that the quantities        of heat stored and delivered are as large as possible. In order        to avoid any risk of the material running away into the earth,        it is advantageously contained in reservoirs of elongate        cylindrical shape or of shape adapted to filling the empty space        generated by the mainly vertical fins moving in rotation.

The invention can be understood more clearly with reference to theaccompanying figures, in which:

FIG. 1 is a view showing a dwelling standing on four piles of theinvention, which piles have two functions since they act both assupports for the dwelling and as heat exchangers for the primary circuitof a reversible heat pump used for heating and for cooling saiddwelling;

FIG. 2 is an enlarged view of an element of FIG. 1;

FIG. 3 is a view showing a dwelling standing on three piles of theinvention, said piles feeding a liquid/air heat exchanger for moderatingthe temperature of replacement air for the dwelling;

FIG. 4 is a section view and shows implementation details of a pile ofthe invention;

FIGS. 5A and 5B are section views on section lines AA and BB of FIG. 4;and

FIG. 6 is an enlarged section view of a pile of the invention in apreferred embodiment.

The figures show that the invention recommends using at least one hollowpile 1 as a heat exchanger for exchanging heat between the soil and afluid, which pile is preferably made of metal and is sunk substantiallyvertically into the soil by screw-sinking. The pile has an inside wall(1 i), and outside wall (1 e) and a wall thickness that is substantiallyconstant. The pile 1 can be made up of a plurality of segments connectedtogether end-to-end in leaktight manner.

The pile 1 has:

-   -   at least one helical and substantially horizontal fin 2 having a        flattened shape and a small pitch, and being suitable for        causing the pile to sink by a few centimeters per turn, when        said pile is caused to move in rotation, said helical fin 2        finding itself united mechanically with and in thermal contact        with the outside wall 1 e of the pile;    -   internal partitioning 3 defining two distinct compartments 11,        12 that communicate with each other at the bottom 13 of the pile        1, namely an axial compartment 11, and an outer compartment 12,        the outer compartment 12 advantageously having a flow section S2        that is significantly smaller than the flow section S1 of the        axial compartment 11;    -   a bottom portion 9 that is of conical shape; and    -   a top flange plate 8 having through openings for pipes 4        communicating in leaktight manner with each of the two        compartments defined by the internal partitioning 3.

In a preferred embodiment that procures particularly good performance,in addition to being provided with the fin(s) 2, the pile 1 is providedwith at least one mainly vertical fin 22. This mainly vertical fin 22advantageously has a length such that it does not extend beyond theouter end of the mainly horizontal fin 2, above which said mainlyvertical fin is placed. Said mainly vertical fin is connected to theoutside wall of the pile 1, preferably by welding. The fin 22 has arounded or beveled end so that, while it is moving in rotation, itpushes away the earth that has previously been broken up under theaction of the mainly horizontal fin 2. After all of the segments formingthe fluid/soil heat exchanger have been put into place by screw-sinking,the void generated by the mainly vertical fin moving in rotation 22 isadvantageously filled with a material that offers good performance asregards heat conduction and storage, or, for certain uses, as regardsstrength. Said material is lean mortar or cement, bentonite, or asubstance having the property of changing stage at a temperature closeto 20° C. and, in any event, greater than 10° C.

The fact that each of the piles of the invention has at least onevertical fin 22 of a width less than the diameter of the mainlyhorizontal fin 2 thus makes it possible to form an empty space that iscoaxial with the pile. This space that is formed by the vertical fin 22moving in rotation being filled with a material 25 having thermalinertia and conductivity greater than those of the earth in which saidpile is sunk. And the material 25 can be chosen from among substancesthat have the feature of going from the solid state to the liquid stateat a temperature greater than 10° C., e.g. from among the family ofnormal paraffins or of isoparaffins.

Under these circumstances, it can be understood that the fluid that iscolder in winter or hotter in summer relative to the soil exchanges heatfirstly with the outside wall of the pile 1, then with the horizontalfin(s) 2 and with the vertical fin(s) 22, and, simultaneously, with themass of filler material 25 that finds itself in thermal contact with thevertical fin(s) 22. Finally, the filler material 25 exchanges heat withthe compacted earth T that finds itself at its periphery, as shown inFIG. 6, the heat finally diffusing to the rest of the soil that has notbeen affected by the operations of putting the piles into place byscrew-sinking.

The piles of the invention are put into place in successive segments.The bottom segment has an end 9 of conical shape that is suitable forpenetrating into the soil, and that makes it possible to close off thecompartments in which the fluid flows. The segments are assembledtogether in leaktight manner by welding, by inter-fitting, or byscrew-fastening, and each segment has one or more helical fins 2 inthermal contact with the outside wall 1 of said pile.

When the piles of the invention are used as foundations for a building,and more specially for a greenhouse or for a lightweight dwelling, eachof them, at its top, is provided with a link piece 10 having fasteningmeans suitable for being secured to the floor 17 or to the bottomstructure of a building 7, and with a side or top opening making itpossible to pass feed and discharge pipes for the fluid. Thus, each ofthe vertical piles of the invention is provided with a top flange plate8 that is secured to the floor 17 or to the bottom structure of abuilding 7 via a link piece provided with orifices for passing the pipes4.

The fluid that exchanges heat with the soil as it passes through thecompartments of the heat exchanger constituted by one or more piles asdescribed and connected together in series or in parallel via pipes 4can be used to feed the primary circuit of a thermodynamic machine 5 ofthe heat pump type.

In order to enable heat exchange to take place between the fluid and thesoil in which the piles of the invention are sunk, the outer compartment12 is connected via pipes 4 to a liquid/air heat exchange unit 15, saidliquid/air heat exchange unit itself being connected via pipes 4 to theaxial compartment 11, which axial compartment 11 co-operates with theouter compartment 12, with the pipes 4, and with the liquid/air heatexchange unit 15 to form a leaktight and sealed circuit that also has atleast one circulator 16.

In order to enable the replacement air for a building to be pre-heatedor to be cooled, the unit 15 passes the replacement air feeding thebuilding, of which said pile forms part of the foundations.

In this way, the use of at least one pile of the invention makes itpossible to implement heating or air-conditioning installations, or airtreatment or air pre-treatment installations.

It is also possible, using at least one pile of the invention, to layfoundations for an industrial or agricultural building, an individual orcollective residential building, or a leisure building, thereby enablingsuch buildings to benefit firstly from foundations that are inexpensiveand that offer particularly good performance, and secondly from heatingand/or cooling installations that have very low energy consumption.

In a simplified embodiment, each of the piles 1 is provided with asingle fin 2 at its bottom, thereby enabling each pile to be implementedin a single segment. In a preferred embodiment, each of the piles 1 isprovided with a plurality of fins 2, each fin being situated at one endof a segment; the segments being assembled together by welding, byinter-fitting, by force-fitting, or by screw-fastening. Thus, themachine that exerts the screw-sinking torque and a vertical pressure onthe successive pile segments can put each segment into place insuccession, a leaktight mechanical connection being formed, e.g. bywelding, at the outside walls of the piles. The operations of sinkingthe pile into the soil are facilitated by the presence of a conicalpiece 9 at the bottom of said pile. Advantageously, said conical piece 9is fastened to the bottom end of a segment using the same means, e.g.screw-fastening, crimping, or welding, as those used for fastening onesegment to the lower segment, so that the segments are identical to oneanother and each of them can then be connected equally well at itsbottom to the conical end-piece or to another segment, and at its topeither to a terminal flange plate or some other type of plate, or toanother segment.

Under all circumstances, each of the piles 1 is equipped with means forcausing a fluid to flow over all or almost all of its length. Such meanscan, for example, be internal partitioning 3 that opens out at itsbottom 13 such that the fluid flows vertically along the length of thetube from top to bottom inside said internal partitioning 3, at thebottom of which said fluid flows out and back up along the inside wallthrough an annular section lying between the outside wall of the axialtube and the inside wall of the pile 1. Advantageously, the outsidediameter of the internal partitioning 3 is close to the inside diameterof the tube constituting the pile 1, in a manner such that the residualannular section S2 lying between the two cylindrical surfaces defined bysaid walls is sufficiently small for the fluid to flow turbulently, evenfor relatively low flow rates. Also advantageously, and in accordancewith an important characteristic of the invention, the internalpartitioning 3 is provided with a section reducer that can be in theform of a projection or protuberance 31 that is placed at a heightcorresponding to the presence of a helical fin in thermal contact withthe outside wall of the pile. This feature makes it possible toaccelerate the fluid passing between the projection 31 and the outsidewall of the tube forming the pile, so that the zone equipped with ahelical fin constitutes a particularly effective heat exchange zone forheat exchange between the earth in which the pile is buried and thefluid flowing inside the pile. This original feature makes it possibleto reduce the sinking depth and thus the cost of the fluid/soil heatexchangers relative to known geothermal probes for the sameeffectiveness. The combination firstly of the action of a metal finhaving a large surface area in contact with the soil even at distancesremote from the axis of the pile, and secondly of the turbulent flow ofthe fluid on either side of a metal wall makes it possible to obtainvery high performance as regards heat exchange.

In FIG. 4, the flow section reducer or projection 31 is in the form asleeve engaged around the internal partitioning 3 at the fin 2.

FIG. 6 shows a preferred embodiment of the invention, particularly asregards the internal partitioning 3. Similarly to the partitioning inthe embodiment shown in FIG. 4, this partitioning forms an axial centralcompartment or passage 11 having a cross-section S1. The outercompartment is subdivided by the partitioning 3 into a plurality ofpassages or cells 12 a running along the inside wall 1 i of the pile 1.There are seven of these passages 12 a in the embodiment shown in FIG.6. They are disposed in such a manner as to be distributed around thecentral axial compartment 11. Each passage 12 a has a substantiallyhalf-moon shape. It can be noted that the partitioning 3 has a wallthickness that is considerable given that it extends from the axialcompartment 11 to the inside wall of the pile 1 between the passages 12a. The partitioning 3 thus occupies more than one half of the section ofthe pile 1. It can be thought of as a solid bar whose axial core hasbeen hollowed out to form the axial compartment 11, and whose outsidesurface has been cut into to form the outer passages 12 a. Since theinternal partitioning 3 comes into contact with the inside wall of thepile 1, it is centered automatically inside the pile 1.

Each passage 12 a has a cross section s2. The sum of the sections s2 ofall of the passages 12 a corresponds to the total section S2. In theinvention, the total section S2 is less than the section S1 of the axialcompartment 11. In addition, as shown in FIG. 6, the two passages 12 asituated at the helical fin 2 are partially filled with a filler elementthat forms a projection or protuberance 31 relative to the outside wallof the partitioning 3. The projections 31 serve to reduce the sectionsof the passages 12 a so that there remains only a reduced section s2′ ineach of them. The fluid is thus forced to flow at high speed along theinside wall of the pile 1 directly at the helical fin 2. Saidprojections or protuberances 31 can be considered as flow sectionreducers.

In practice, the partitioning 3 can be made by extrusion so that it hasa constant cross-section over its entire length. The partitioning 3 canbe made of metal or of a plastics material. Preferably, the partitioning3 is made of a plastics material so as to avoid heat exchange betweenthe central compartment 11 and the outer compartment formed by sevenpassages 12 a. The flow section reducers or projections 31 can be in theform of inserts mounted inside the passages 12 a. In a variant, the flowsection reducers or projections 31 can be formed directly by thepartitioning or by the pile, e.g. in the form of internal extensions ofthe fins.

The fluid thus exchanges heat with the soil in which the piles 1 aresunk. This exchange is made more effective and faster by means of theaction of the fins 2 that have a large surface area in contact with thesoil and are in thermal contact with the metal tube constituting thepile. The fluid flowing in the piles 1 is then collected in pipes 4 thatconvey it to at least one system 5 for heating or cooling premises 7,said premises 7 preferably, but not necessarily, being built onfoundations formed by one or more piles of the invention.

In a particularly advantageous embodiment shown in FIGS. 1 and 2, theheating or cooling system 5 is constituted by a water/water heat pumpthat is preferably reversible and whose primary circuit exchanges heatwith one or more piles connected to the system 5 via a circuit 4, andwhose secondary circuit exchanges heat with a circuit 6, e.g. alow-temperature under-floor heating circuit.

In a simplified embodiment shown in FIG. 3, the circuit 4 collecting thefluid flowing through the pile(s) of the invention is connected to anair heat exchanger unit 15, i.e. to an air/fluid heat exchanger, thereplacement air for the premises going through said exchanger. Such aheating and cooling system, which is described, in particular, in PatentApplication WO 2006/109003, makes it possible to procure all of thefeatures of systems known as “Canadian wells” (or as “Provencal wells”or indeed as “Californian wells”) while requiring earthworks that areinexpensive, and a small footprint, and while facilitating maintenanceoperations.

In the simple example shown by FIG. 3, three piles 1 of the inventionare used. Each of these piles has fins 2 and a conical bottom end 9enabling it to be sunk by screw-sinking and facilitating heat exchangewith the soil. The piles are provided with internal partitioning 3inside which the fluid flows, the fluid in this example being water,optionally with anti-freeze added. This fluid is collected by a circuit4 that is preferably buried at a depth of a few tens of centimetersbelow ground level. The fluid flows continuously by means of the actionof a pump or circulator 16 so that, depending the current climateconditions, it exchanges heat with the new air fed into the premisesunder the action of a fan (not shown) that causes said new air to flowthrough an air heat exchanger unit 15 in which the fluid that benefitsfrom the heat exchange with the soil flows, which heat exchange takesplace due to said fluid flowing in the piles and is made particularlyeffective by means of the presence of the helical fins 2. In order toimprove heat-exchange capacities, and in order to make it possible tooptimize operation in day/night cycles, all or some of the partitioningor of the zone at the periphery of the tube that is vacated by thecompacting of the earth due to the mainly vertical fin 22 moving inrotation can be filled with a substance having the property of changingstate at a temperature close to the looked-for comfort temperature, e.g.20° C. and in all cases greater than 10° C. For example, this substanceis chosen from among paraffins that offer the property of storing anddelivering about 50 kilocalories per gram, when crossing theirchange-of-state thresholds. This particularly advantageous embodimentmakes it possible to improve significantly the performance ofliquid/soil heat exchangers of the invention, without significantlyincreasing their cost. In particular, this embodiment makes it possible,during summer seasons, to extract large quantities of heat during theday due the change of state from solid to liquid. This is made possibleby previously freezing the paraffins during the night when the outdoortemperature is at a temperature lower than the melting point of theparaffins, such freezing resulting from the paraffins that are containedin the walls forming the partitioning 3 and/or filling the hollowcylinder going from the liquid state to the solid state.

At the top of each of the piles of the invention, a flange plate 8 isprovided that serves as a cap and to which the internal portioning canbe fastened, thereby defining an axial compartment and an outercompartment. The diameter of the tube forming the internal partitioningis chosen so that there remains only a flow space of small sectionbetween the partitioning and the outside wall of the pile, so that thefluid flows turbulently in this portion of the pile. Preferably, thepartitioning wall has extra thickness or a protuberance at the externalfin(s), such that heat exchange between the fluid and the wall of thepile is facilitated in this zone that has the advantage of highpotential for thermal transmission to the surrounding environmentconstituted by the soil.

In general, it is possible to use any type of coupling with varioussystems for heating, air-conditioning, pre-heating or coolingresidential premises or replacement air for residential premises, and inparticular the couplings with air-to-air, air-to-water, water-to-water,water-to-air, refrigerant-to-water or refrigerant-to-air heat pumps,without thereby going beyond the ambit of the invention.

The invention is preferably used for building lightweight leisuredwellings that require shallow or medium-depth foundations and that needto be frost-protected by heat exchange with the soil, even while theyare vacant. In this particular situation, the fluid can be caused toflow between the soil and at least one air heat exchanger unit by a pumppowered by photovoltaic solar collectors. The invention is alsoparticularly suitable for use in building agricultural or industrialstructures such as greenhouses or sheds or warehouses, it beingunderstood that these preferred uses are in no way limiting.

Insofar as the piles of the invention are used for both of theirfunctions, i.e. both as heat exchangers and also as lightweightfoundations, a link piece 10 is provided between firstly the top of eachof the piles 1, which top is equipped with a flange plate 8, andsecondly the floor 17 or a bearing piece of the bottom structure of thebuilding 7.

1. A hollow pile suitable for being sunk substantially vertically intothe soil by screw-sinking, the pile comprising an inside wall, anoutside wall and a thickness of wall, said pile further comprising: atleast one helical fin having a flattened shape and a small pitchsuitable for causing the pile to be sunk by a few centimeters per turn,when said pile is caused to move in rotation, the helical fin findingitself united mechanically with and in thermal contact with the outsidewall of the pile; and internal partitioning defining an axialcompartment and an outer compartment that communicate with each other atthe bottom of the pile; said hollow pile being characterized in that:the helical fin is in direct thermal contact with the outer compartmentthrough the thickness of outside wall of the pile; and the outercompartment has a flow section that is significantly smaller than theflow section of the axial compartment.
 2. A vertical pile according toclaim 1, wherein the outer compartment is provided with a flow sectionreducer at at least one helical fin.
 3. A vertical pile according toclaim 2, wherein the flow section reducer is integral with the internalpartitioning.
 4. A vertical pile according to claim 1, made up of aplurality of segments assembled together in leaktight manner by welding,by inter-fitting, or by screw-fastening, and wherein each segment isprovided at its bottom with a helical fin in thermal contact with theoutside wall of the pile.
 5. A vertical pile according to claim 1,further comprising a top flange plate having through orifices forpassing pipes that communicate in leaktight manner with respective onesof the two compartments defined by the internal partitioning, the topflange plate being secured to a floor or to a bottom structure of abuilding via a link piece provided with through orifices for passing thepipes.
 6. A vertical pile according to claim 1, wherein the fluidcirculating in the compartments inside the pile is used to feed theprimary circuit of a thermodynamic machine of the heat pump type.
 7. Avertical pile according to claim 1, wherein the internal partition ispartially filled with a substance having the property of changing stateat a temperature close to 20° C., and preferably with a substance basedon paraffin.
 8. A vertical pile according to claim 1, wherein the fluidextracted from the outer compartment is conveyed via pipes to aliquid/air heat exchange unit, said unit itself being connected viapipes to the axial compartment, the assembly that is made up of theouter compartment, of the pipes, of the unit, and of the axialcompartment forming a leaktight and sealed circuit further comprising atleast one circulator.
 9. A vertical pile according to claim 8, whereinthe unit passes the replacement air feeding the building of which saidpile constitutes part of the foundations.
 10. An installation forheating, conditioning, treating or pre-treating air, said installationincluding at least one vertical pile according to claim
 1. 11.Foundations for an industrial, agricultural, individual or collectiveresidential, or leisure building, said foundations including at leastone vertical pile according to claim 1.